Bandsaw cutting-machine



United States Patent Gaston Gasne Sainte-Genevieve-des-Bois, and Jean Le Metayer, Bruyeres-le-Chatel,

[72] Inventors France [21] Appl. No. 802,976

[22] Filed Feb. 27, 1969 [45] Patented Nov. 3, 1970 [73] Assignee Commissariat a LEnergie Atomique Paris, France [32] Priority March 22, 1968 [33] France [54] BANDSAW CUTTING-MACHINE 11 Claims, 3 Drawing Figs.

[52] U.S.C1 83/165,

83/167, 83/168, 83/169, 83/170, 83/201.15 [51] Int. Cl 826d 1/54 [50] Field ofSearch 83/165,

167, 168,169, 170, l71,20120l.l5,925

[56] References Cited UNITED STATES PATENTS 501,554 7/1893 Wilson 83/168 3,069,950 12/1962 Hensley 83/168 Primary Examiner-James M. Meister Attorney-Craig, Antonelli, Stewart and Hill ABSTRACT: In a bandsaw cutting-machine, a box for the recovery of fumes given off as a result of spark formation during operation of the bandsaw is placed above the work table so as to enclose the workpiece and is provided with a slit through which the band is permitted to pass. A second box placed beneath the table and partly filled with water has two communicating compartments located on each side of the band and a central drawer between the two compartments forms a seal which is traversed by the band. Spark deflectors are mounted beneath the workpiece and associated with a mechanism for adjusting their lateral positions within the second box with respect to the moving band and means are provided for producing a vacuum within both boxes.

BANDSAW CUTTING-MACHINE The present invention relates to a bandsaw cutting-machine which is primarily although not solely intended for cutting bars of nuclear material and in particular rods or slugs of uranium metal.

It is known that the cutting of metallic parts by means of a continuously moving bandsaw inevitably causes projections of sparks under the action of the saw teeth. These sparks consist of small particles of metal which are heated to incandescence as a result of the very high degree of friction which is developed when the metallic workpiece is in contact with the bandsaw at the high running speeds usually adopted. It is also known that the formation of sparks is accompanied by more or less toxic fumes which result especially from the cooling of the metallic particles which are projected. In the case in which the metal considered is uranium and if no special precaution is taken, these sparks can exhibit a certain degree of radioactivity and cause contamination of the atmosphere surrounding the bandsaw cutting-machine, the fumes produced being also particularly toxic for users. It is known in particular that the measured radioactivity must not exceed a given threshold which is designated by the term of maximum permissible concentration. in order that this concentration should not be attained, a cutting-machine of this type which is employed in particular for cutting slugs of radioactive materials must therefore be equipped with safety devices which are added to its main components in order to ensure that the incandescent particles are immediately extinguished and recovered and that the fumes which are produced are removed at the same time.

With this objective, the bandsaw cutting-machine considered, which comprises a flexible endless band driven in rectilinear motion over a metallic workpiece having a horizontal axis and mounted on a carriage which is supported on a work table and which is endowed with a feed motion along said table at right angles to the direction of displacement of said band, is characterized in that provision is made for a first box for the recovery of fumes produced which covers said workpiece above said table and is provided with a slit for the passage of said band, a second box which is partly filled with water and placed beneath said table, said second box having two communicating compartments placed on each side of said band, a drawer forming a seal traversed by said band and fitted between the two compartments, spark deflectors mounted beneath said workpiece and associated with a mechanism for controlling the lateral positions thereof within said second box with respect to said band and suction intakes for lowering the pressure of the atmosphere of said boxes.

Further properties of a bandsaw cutting-machine in accordance with the invention will become apparent from the following description of one example of construction which is given by way of indication and not in any limiting sense, reference being had to the accompanying drawings, wherein:

FIG. 1 is a diagrammatic elevational view of a cuttingmachine in accordance with the invention;

FIG. 2 is a perspective view on a large scale showing a portion of the cutting-machine of FIG. 1 and illustrating in particular the safety devices with which said machine is provided;

FIG. 3 is an enlarged view showing a detail of FIG. 2.

From FIG. 1, it is seen that the cutting-machine under consideration comprises essentially a bandsaw l which is driven in a continuous movement of displacement by means of two drums 2 and 3 having parallel axes, said drums being mounted at the top and bottom of the frame 4 of the machine for the purpose in particular of carrying out the downward vertical displacement of the bandsaw l which is in contact with the metallic workpiece 5 to be cut. Said workpiece 5 which is usually in the form of a cylindrical slug, especially of uranium or like nuclear material, is clamped at the ends by means of collars 6 and 7 of a carriage (not shown in the drawings) which is adapted to cooperate with guide grooves 8 formed in a horizontal table 9, the orientation of said grooves being such as to permit a displacement of the carriage in a direction parallel to the plane of the bandsaw l, the axis of said slug 5 being located at right angles to said displacement. The table 9 l is adapted to rest on a support 10 which is rigidly fixed to the frame 4 of the machine and provided with a central slot 11 through which the bandsaw 1 is permitted to pass vertically in the downward direction.

In accordance with the invention, the bandsaw cuttingmachine which is illustrated in the drawings is equipped with different safety devices which make it possible in particular to control and remove the sparks or particles of metal which have been heated to incandescence and have broken away from the slug 5 as a result of contact with the bandsaw l, as well as to remove the toxic fumes produced by said sparks. The machine thus comprises in particular two superposed boxes 12 and 13 which are respectively provided above and beneath the table 9 and which are shown more clearly and in greater constructional detail in the perspective view of FIG. 2.

As shown in this FlG., the upper box 12 is adapted to cover the slug 5 and is preferably constructed in two demountable sections consisting of a body 14 and a transparent cover 15 for the purpose of gaining ready access to the slug and in particular in order to replace this latter or to remove the two parts obtained on completion of the cutting operation by the bandsaw 1. The body 14 of the box 12 is provided with a slot 16 through which the bandsaw is intended to pass. Said bandsaw is guided above the slug 5 by means of two rollers 17 and 18, the axes of said rollers being parallel to the plane of the saw, namely perpendicular to the axis of the slug 5. The atmosphere of the upper box 12 is put under reduced pressure by means of an external pump 19 (as shown in FIG. 1), the suction side ofwhich is connected to the interior of the box by means of a flexible hose 20. The fumes produced by the sparks formed by the bandsaw are collected in said box 12 and, under theseconditions, are immediately sucked-out by the pump 19 and then discharged to the exterior of the machine after suitable filtration.

The second box 13 which is placed beneath the first box 12 also has a body 21 and a transparent cover 22 which constitutes the front face of said box. The body 21 is provided at the center with a flanged section 23 which surrounds the bandsaw blade 1 and defines within the box 13 two adjacent compartments which communicate with each other behind the flanged section 23. These compartments are filled with water up to a mean level which is not shown in the drawings, the water being fed into the box 13 through a pipe 24 extending from a supply tank 25 and being discharged through a second pipe 26. Preferably, the supply tank 25 and the discharge pipe 26 are connected in a closed cycle by means of a circulating pump 27 (shown in FIG. 1) which provides continuous circulation of water within the box 13. Beneath one of said compartments, the box 13 is provided with a container 28 which communicates with the box through an opening 29 and is intended to recover the metallic particles projected onto the slug 5 as a result of the motion of the bandsaw I. Said particles, which are initially incandescent, are extinguished as they come into contact with the water of the box 13 and collect at the bottom of the container 28 under the action of gravity. A leak-tight cover 30 serves to gain access to the bottom of said container.

During its continuous motion within the flanged section23 of the box 13, the bandsaw is guided by two rollers 31 and 32 which are similar to the rollers 17 and 18 ofthe first box 12. In addition, two members for deflecting the sparks produced 'by the bandsaw are mounted immediately beneath said rollers and have the shape of two triangular prisms 33 and 34, the inclined faces of which are oriented symmetrically on each side of the bandsaw in order to ensure deflection of the sparks and to bring these latter into contact with the water contained within the box 13. Advantageously, said prismatic deflectors 33 and 34 are connected by means of an'operating rod 35 to an external device 36 which serves to vary the lateral position of said deflectors with respect to the bandsaw in order that the deflection of sparks should thus be regulated under the best conditions, Finally, the box 13 is provided with two suction intakes 37 and 38 which are located above the level of water wlthln mild box and connected by means of a common pipe 39 to mt external suction hone 40 which is In turn connected to the pump l9 in the same manner as the suction hose of the first box l2.

The equipment of the bandsaw cutting-machine is completed by means of two ancillary systems which permit on the one hand guiding of the bandsaw as this latter passes through the boxes 12 and 13 and, on the other hand, the final recovery of all the particles which may not already have been collected within said boxes. To this end, the cutting-machine is provided firstly with a drawer-seal 41 which is fitted with an external operating handle 42 and made up of a metallic casing 43 filled with a suitable thickness of asbestos 44 against which the bandsaw slides as this latter traverses the flanged section 23 of the box 13. A further advantage of said drawer lies in the fact that it permits direct access to the bandsaw l as well as the replacement of this latter as and when the need arises. There is also mounted beneath the box 13 a collecting vessel 45 supported by a plate 46 which is added to the body 21 of the box 13. Said vessel is shown in constructional detail on a larger scale in FIG. 3 and is composed in particular of two coaxial cylindrical casings 47 and 48 which contain a suitable quantity of graphite in either granular or powdered form. Said casings are split laterally along generator-lines at 49 in the case of the first casing and at 50 in the case of the second casing so as to permit the passage of the bandsaw l, the graphite contained within the vessel being intended to absorb the final sparks which may be carried down by the teeth of the bandsaw. The casings 47 and 48 are provided respectively with two orifices 51 and 52 in order that they can be filled with graphite when said two orifices are in oppositely-facing relation, this coincident relationship being obtained by causing the pivotal motion of the outer casing 47 with respect to the inner casing 48. Once the filling operation has been completed, the two casings are relatively displaced and interlocked by means of a cruciform locking member 53. The casing 48 has a welded end-wall 54 which prevents the graphite from escaping and is provided only with a slit for the passage of the bandsaw blade.

The bandsaw cutting-machine as constructed in the manner hereinabove described affords particularly reliable operation, especially in the case in which the metallic bar or slug to be cut is formed of a hazardous metal such as uranium in particular The production of a vacuum within the upper and lower boxes results in the immediate discharge of all the fumes produced whilst the sparks formed as the saw-blade comes into contact with the slug are immediately extinguished and projected into the water of the lower box before being recovered in the evacuation container of said box. The apparatus as it whole is of simple design, practical to use and has a degree of efficiency which permits operation for long periods oftlme in complete safety. ln particular, the apparatus calls for only a minumum amount of maintenance and makes it possible to change the saw-blade without having to cut or reweld said blade.

As will be readily understood, the invention is not limited in any sense to the example of construction herein described and illustrated in the accompanying drawings or to the mode of application which has been more especially contemplated. In particular, although the cutting-machine considered provides essential advantages when used for cutting bars or slugs of radioactive metals, it remains evident that the machine could equally well be employed in'the case-of different metals and covers said workpiece above said table and is provided with a slit for the passage of said band, a second box which is partly filled with water and placed beneath said table, said second box having two communicating compartments placed on each side of said band, a drawer forming a seal traversed by said band and fitted between the two compartments, spark deflectors mounted beneath said workpiece and associated with a mechanism for adjusting the lateral positions thereof within said second box with respect to said band and suction intakes for lowering the pressure of the atmosphere of said boxes.

2. A cutting-machine in accordance with claim 1, characterized in that said band is guided in the rectilineal motion thereof through said boxes by means of sets of rotating rollers having axes parallel to the plane of said band.

3. A cutting-machine in accordance with claim I, characterized in that said boxes are advantageously provided with a transparent front face.

4. A cutting-machine in accordance with claim 1, characterized in that said first box is constructed in two demountable sections so as to permit of positioning or withdrawal of the metallic workpiece to be cut.

5. A cutting-machine in accordance with claim 1, characterized in that, after passing through said second box, said band traverses a safety collecting vessel containing a powdered or granular material.

6. A cutting-machine in accordance with claim 5, characterized in that said powdered material is graphite.

7. A cutting-machine in accordance with claim 5, characterized in that said collecting vessel is constituted by two hollow cylindrical casings in coaxial and interengaged relation, said casings being capable of pivotal motion one inside the other prior to interlocking by means of a locking member, said cylindrical casings being provided with a slit along a generator-line for the passage of said band.

8. A cutting-machine in accordance with claim 1, characterized in that said second box is provided beneath at least one compartment thereof with a container for recovering metal particles which are carried down by said band and projected into the water of said box by said deflectors.

9. A cutting-machine in accordance with claim 8. characterized in that said deflectors have the shape of triangular prism.

10. A cutting-machine in accordance with claim 1, characterized inthat the water of said second box is circulated continuously within an external loop system comprising a circulating pump.

11. A cutting-machine in accordance with claim ll, characterized in that said drawer has a metallic frame fitted with an external operating handle and is filled with asbestos which comes into contact with said band. 

